The Stag, the Wolf, and the Sheep

A STAG asked a Sheep to lend him a measure of wheat, and said
that the Wolf would be his surety. The Sheep, fearing some fraud
was intended, excused herself, saying, "The Wolf is accustomed to
seize what he wants and to run off; and you, too, can quickly
outstrip me in your rapid flight. How then shall I be able to
find you, when the day of payment comes?'